{"id":2678,"date":"2017-06-16T21:50:30","date_gmt":"2017-06-16T13:50:30","guid":{"rendered":"http:\/\/www.qdabc.cn\/?p=2678"},"modified":"2017-06-16T21:50:30","modified_gmt":"2017-06-16T13:50:30","slug":"es6%e5%ad%a6%e4%b9%a0%e7%ac%94%e8%ae%b0","status":"publish","type":"post","link":"http:\/\/www.qdabc.cn\/?p=2678","title":{"rendered":"ES6\u5b66\u4e60\u7b14\u8bb0"},"content":{"rendered":"

let<\/span>
\nlet\u7c7b\u4f3c\u4e8evar\uff0c\u90fd\u7528\u4e8e\u5bf9\u53d8\u91cf\u7684\u5b9a\u4e49\u3002\u4e0b\u9762\u662flet\u4e8evar\u7684\u4e0d\u540c\uff1a<\/p>\n

1\u3001let\u53ea\u4f5c\u7528\u4e8e\u81ea\u5df1\u7684\u5757\u7ea7\u4f5c\u7528\u57df\u5185\u5bb9\u3002<\/span><\/p>\n

{\r\n   \tvar a = 1;\r\n   \tlet b = 2;\r\n   }\r\nconsole.log(a); \/\/1\r\nconsole.log(b); \/\/\u62a5\u9519 b is not defined<\/pre>\n
\u8fd9\u8868\u660e\uff0clet\u58f0\u660e\u7684\u53d8\u91cf\u53ea\u5728\u5b83\u6240\u5728\u7684\u4ee3\u7801\u5757\u6709\u6548\u3002<\/p>\n
2\u3001let\u4e0d\u5141\u8bb8\u91cd\u590d\u58f0\u660e<\/span>
\nlet\u4e0d\u5141\u8bb8\u5728\u76f8\u540c\u4f5c\u7528\u57df\u5185\uff0c\u51fa\u73b0\u540c\u4e00\u4e2a\u53d8\u91cf\u3002<\/p>\n
3\u3001let\u4e0d\u5b58\u5728\u53d8\u91cf\u63d0\u5347<\/span><\/p>\n
console.log(a); \/\/undefined\r\nvar a = 1;\r\nconsole.log(b); \/\/\u62a5\u9519 b is not defined\r\nlet b = 2;<\/pre>\n
let\u5982\u679c\u5148\u4f7f\u7528\u518d\u5b9a\u4e49\uff0c\u5c31\u4f1a\u62a5\u9519\uff0c\u8fd9\u79cd\u53eb\u505a\u201c\u6682\u65f6\u6027\u6b7b\u533a\u201d\u3002\u6240\u4ee5\uff0clet\u53ea\u80fd\u5148\u5b9a\u4e49\u540e\u4f7f\u7528\uff0c\u8fd9\u4e5f\u662fES6\u6240\u63d0\u5021\u7684\u7528\u6cd5\u3002<\/p>\n
const<\/span>
\nES6\u6269\u5c55\u4e86\u53ea\u8bfb\u5e38\u91cf\uff0cconst\u5c31\u662f\u58f0\u660e\u53ea\u8bfb\u5e38\u91cf\u7684\u547d\u4ee4\u3002\u4e00\u65e6\u58f0\u660e\uff0c\u5e38\u91cf\u7684\u503c\u5c31\u4e0d\u80fd\u6539\u53d8\u3002<\/p>\n
const a = 1;\r\nconsole.log(a); \/\/1\r\na = 2; \/\/\u62a5\u9519Assignment to constant variable.<\/pre>\n
const \u58f0\u660e\u5e38\u91cf\u540e\u5fc5\u987b\u8d4b\u503c\uff0c\u5e76\u4e14\u548clet\u4e00\u6837\uff0c\u53ea\u5728\u58f0\u660e\u6240\u5728\u7684\u5757\u7ea7\u4f5c\u7528\u57df\u5185\u6709\u6548\u3002<\/p>\n
const a; \/\/\u62a5\u9519 Missing initializer in const declaration\r\nif (true) {\r\n  const b = 5;\r\n}\r\nconsole.log(b); \/\/\u62a5\u9519 b is not defined\r\n<\/pre>\n
=>\u7bad\u5934\u51fd\u6570<\/span>
\nES6\u6269\u5c55\u4e86\u7bad\u5934\u51fd\u6570\u201c=>\u201d<\/p>\n
var f = v => v;\r\n\/\/\u7b49\u540c\u4e8e\r\nvar f = function(v) {\r\n  return v;\r\n};<\/pre>\n
\u5982\u679c\u7bad\u5934\u51fd\u6570\u4e0d\u9700\u8981\u53c2\u6570\u6216\u9700\u8981\u591a\u4e2a\u53c2\u6570\uff0c\u5c31\u4f7f\u7528\u4e00\u4e2a\u5706\u62ec\u53f7\u4ee3\u8868\u53c2\u6570\u90e8\u5206\u3002<\/p>\n
var f = () => 5;\r\n\/\/ \u7b49\u540c\u4e8e\r\nvar f = function () { return 5 };\r\n\r\nvar sum = (num1, num2) => num1 + num2;\r\n\/\/ \u7b49\u540c\u4e8e\r\nvar sum = function(num1, num2) {\r\n  return num1 + num2;\r\n};<\/pre>\n
\u5982\u679c\u7bad\u5934\u51fd\u6570\u7684\u4ee3\u7801\u5757\u90e8\u5206\u591a\u4e8e\u4e00\u6761\u8bed\u53e5\uff0c\u5c31\u8981\u4f7f\u7528\u5927\u62ec\u53f7\u5c06\u5b83\u4eec\u62ec\u8d77\u6765\uff0c\u5e76\u4e14\u4f7f\u7528return\u8bed\u53e5\u8fd4\u56de\u3002<\/p>\n
var f = (n,m) => {\r\n   var z = n+m;\r\n   return z;\r\n};\r\n\/\/\u7b49\u540c\u4e8e\r\nvar f = function(n,m){\r\n\tvar z = n+m;\r\n\treturn z;\r\n}<\/pre>\n
…\u6269\u5c55\u8fd0\u7b97\u7b26<\/span>
\n\u6269\u5c55\u8fd0\u7b97\u7b26\uff08…\uff09\u662f\u5c06\u4e00\u4e2a\u6570\u7ec4\u8f6c\u4e3a\u7528\u9017\u53f7\u5206\u9694\u7684\u53c2\u6570\u5e8f\u5217\u3002<\/p>\n
bar = function(a, b, ...args) {\r\n    console.log(a);  \/\/a\r\n    console.log(b);  \/\/b\r\n    console.log(args); \/\/['c','d','e']\r\n}\r\nbar('a', 'b', 'c', 'd', 'e');<\/pre>\n
…\u8fd0\u7b97\u7b26\u8fd8\u53ef\u4ee5\u5feb\u901f\u5c06\u4e00\u4e2a\u5b57\u7b26\u4e32\u8f6c\u4e3a\u6570\u7ec4\u683c\u5f0f<\/p>\n
let str = 'hello-es6';\r\nlet strArr = [...str];\r\nconsole.log(strArr);  \/\/[\"h\", \"e\", \"l\", \"l\", \"o\", \"-\", \"e\", \"s\", \"6\"]<\/pre>\n
\u4f7f\u7528…\u8fd0\u7b97\u7b26\u5feb\u901f\u5408\u5e76\u6570\u7ec4<\/p>\n
let arr1 = ['a', 'b', 'c'];\r\nlet arr2 = ['d', 'e', 'f'];\r\nlet arr3 = ['x', 'y', 'z'];\r\nlet arr4 = [...arr1, ...arr2, ...arr3];\r\nconsole.log(arr4);  \/\/ [\"a\", \"b\", \"c\", \"d\", \"e\", \"f\", \"x\", \"y\", \"z\"]<\/pre>\n
 <\/p>\n
\u6b22\u8fce\u5206\u4eab\u672c\u6587\uff0c\u8f6c\u8f7d\u8bf7\u4fdd\u7559\u51fa\u5904\uff1a\u524d\u7aefABC<\/a> » ES6\u5b66\u4e60\u7b14\u8bb0<\/a><\/p>","protected":false},"excerpt":{"rendered":"
let let\u7c7b\u4f3c\u4e8evar\uff0c\u90fd\u7528\u4e8e\u5bf9\u53d8\u91cf\u7684\u5b9a\u4e49\u3002\u4e0b\u9762\u662flet\u4e8evar\u7684\u4e0d\u540c\uff1a 1\u3001let\u53ea\u4f5c\u7528\u4e8e\u81ea\u5df1\u7684\u5757\u7ea7\u4f5c\u7528\u57df\u5185\u5bb9\u3002 { var a = 1; let b = 2; } console.log(a) […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[186],"tags":[9,26],"_links":{"self":[{"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/posts\/2678"}],"collection":[{"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2678"}],"version-history":[{"count":1,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/posts\/2678\/revisions"}],"predecessor-version":[{"id":2679,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=\/wp\/v2\/posts\/2678\/revisions\/2679"}],"wp:attachment":[{"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2678"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2678"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.qdabc.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2678"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}